重複僧帽弁口を合併した高齢者僧帽弁副組織の1例

Accessory Mitral Valve Tissue Combined with Double-orifice Mitral Valve in an Elderly Patient：Report of a Case

はじめに　僧帽弁副組織は，僧帽弁前尖と心室中隔との間にパラシュート様の構造物として認められる，まれな先天性奇形である．大動脈弁下狭窄をきたすことが多く，またほかの先天性疾患を合併することも知られている1）．そのため多くの症例が小児期に診断されて外科的治療が行われ，成人期に認められることはきわめてまれである．われわれは，大動脈弁下狭窄を呈さず成人期まで無症状で経過したため，左室内腫瘍との鑑別を要した高齢者重複僧帽弁口合併僧帽弁副組織の1例を経験した．

A 73-year-old man underwent echocardiography in order to assess any cardiac risk prior to surgery for renal cancer, and a large mobile mass was incidentally identified in his left ventricular outflow tract. Since a metastatic cardiac tumor was suspected, surgical resection of the mass was performed under cardiopulmonary bypass and hypothermic circulatory arrest. The mass had peduncles in the anterior leaflet of the mitral valve, the interventricular septum, and the papillary muscles. They were carefully removed by approaching through the aortic valve, and macroscopically suspected to be accessory mitral valve tissue. We observed the mitral valve via a transseptal approach to assess the function of the mitral valve and, as a result, a double-orifice mitral valve was identified. We should bear in mind that asymptomatic accessory mitral valve tissue can sometimes be detected in elderly patients, and is commonly associated with other congenital cardiac anomalies.